Mineral oil compositions



and temperature.

Patented July 22, 1952 UNITED, STATES PATENT OFFIQE MZINEBAL on. COMPOSITIONS Albert G. Rocchini, Springdale, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application September 16,1948, Serial No. 49,658

Claims. (01. 252+51.5)'

This invention relates to mineral oil compositions, and in particular concerns mineral oil compositions adapted to protect ferrous and other metal surfaces with which they come in contact from rusting and other types of corrosion.

As is well known, simple mineral oil films afford only limited protection to metal surfaces against rusting and other types of corrosion, and in general cannot be relied upon to provide sufficient protection in the presence of moisture or even under conditions of high humidity. Consequently, it has become common practice to employ corrosion inhibitors or anti-corrosion agents as additives in mineral oil compositions for the purpose of providing additional protection against rusting and corrosion. Such additives have been used in various types of lubricating compositions, such as machine oils, turbine oils, internal combustion engine and diesel lubricating oils, greases, etc., as well as'in slushing oils and the like. The anti-corrosion agents heretofore employed in this manner, however, have not proved entirely satisfactory under present-day service conditions. Certain of such agents do not provide adequate protection against corrosion under extreme conditions of moisture, humidity,

Others, while being satisfactory for use in mineral oil compositions which are employed in the presence of only relatively pure water or water vapor, do not provide protection against corrosion by salt water or other aqueous solutions. Others deleteriously afiect certain desirable properties of the compositions in which they are used, e. g., lubricating value, demulsibility, etc.

Accordingly, it is an object of the present invention to provide mineral oil compositions which protect metal surfaces with which'they come in contact against rusting and corrosion under extreme conditions ofservice. 7

Another object is to provide mineral oil compositions capable of protecting metal surfaces against corrosion even by salt water.

A furtherobject is to provide anti-corrosion I lubricating oil compositions suitable for use uning detailed description of the invention, and

variousv advantages not specifically referred to hereinwill occur'to-those skilled in the art upon employment of the invention in practice.

I have now found that the above objects and attendant advantages may be realized by incorporating into mineral oil compositions as an anti-corrosion additive a minor amount of a water-insoluble amide or imide of a substituted aliphatic dicarboxylic acid containing as a substituent a hydrocarbon radical such as an alkyl, aryl, alkenyl, aralkyl, or cycloalkyl radical. I have found that amides and imides ofthis class are particularly well adapted for use as anticorrosion additives for mineral oils, since they effectively inhibit rusting and corrosion of metals under very drastic corrosion conditionsand at the same time do not adversely affect the lubricating properties of theoil. Mineral oil compositions containing such products as corrosion inhibitors are especially well suited for use as lubricants in the presence of water and water vapor, e. g., as steam turbine oils and the like, since they provide adequate protection against corrosion and do not tend to emulsify withthe water.

The amides and imides may be made by any suitablemethod. They can be made eficiently by reacting ammonia or a primary or secondary amine with an anhydride of one of the substituted aliphatic dicarboxylic acids. The reaction usually takes place readily with the evolution of heat, but in some cases mild heating is desirable to start the reaction. Because of the exothermic nature of the reaction, it is usually preferable to add the ammonia or amine to the substituted aliphatic dicarboxylic acid in small increments so that the temperature does not rise uncontrollably. To insure adequacy of reaction the mixture should attain a temperature of about 250 F. or higher. If the exothermic heat of reaction is not suflicient under the conditionsof operation to raise the temperature to this point, the mixture should be heated. It appears that an amide is the product initially formed."particularly at the lower reaction temperatures, and when ammonia or a primary amine is employed the resulting amide may be converted at least in part to the imide at more elevated temperatures. The reaction products may be referred to as amido reaction products as they may be composed of the amide or the imide or mixtures of the two. I prefer to employ about equimolecular quantities of the anhydride and'the ammonia or amine since entirely satisfactory products are obtained under these conditions. However, the ammonia or amine may be used in excess so as to produce at the lower reaction temperatures aproduct containing a substantial proportion of the di-amide.

. rhexyl,;:ethylcyclohexyl, cycloheptyl, etc.

The amides and imides employed in accordance with the present invention may also be prepared from the substituted aliphatic dicarboxylic acids directly. Since at low temperature conditions the reaction product between ammonia or a primary or secondaryamine and .a substituted aliphaticdicarboxylic acid is a'salt, itis necessary in order to produce the amide or imide to mix the acid and the nitrogen compound at an elevated temperature, which should be at least 250 F., or to heat the mixture prepared atalow-temperature to such an elevated temperature. .The elevated temperature should :be maintained for ---.a time suflicient to cause the decomposition; ofa salt between the substituted aliphatic dicarboxylic.

acid and the ammonia or amine and thegp'roduction of the corresponding amide or imide. "It is important to insure that any salt';,.fo'rmed is converted to the amide'for imide as the salts are ,generallyhighly wateresoluble.andtherefore un- -.-suita ble,,for -usein the compositions oflthepresgentgi'nventionr r JI'heamidesand imides that are. adaptedffor use-.in. the compositions ofithe invention, :and pre- ,paredgfor example as .described. above, are rela- -.tively high-boiling, light-colored liquids of medinin=viscosity.todarkerwolored semi-liquids or soft.resinous.solids. They-are sufliciently soluble =in.miner.al. oils toact :as very effective corrosion inhibitors inmineral. oil. compositions. .Theyare !.a1so s luble .in .such .orga-nic solvents as hexane rchloroformand-benzene.

:It will she obvious to thoseskilled .in .the/art athat .within-the-general. descriptionof th amides ..and .;imides ggiven above-compounds .of varying :degreesof solubility in mineral .oil are included. l-The amides or.imides thatare especially. suitable for use inthe= .pr.esentlcompositions are .those which .are..soluble..in'.the mineraLoil .that ;forms the haseforitlie compositions inanamount :equal ..to at 1east.-0.0.05,per cent by weightpflthe oil at atmospheric temperatures. .The preferred zamides pr imides: arethose which ar.e-derivatives -.ofl.subs'tituted aliphatic .dicarboXylic acids ,in :wliich..,the ,..s1ibstituent group is .a hydrocarbon -radicaltcontainingoatleast-'6 carbon atoms and ipreferably an,a1ky1 group containing at least 6 .carbori .atoms'. jMoreov'er, in. .cases where ammoniaor' an amine containing a relatively small numberof carbon atoms is employed for the pro- .duction of :the amide .or imide,'the substituent of ithedicarb'oxylic acid should containa relatively ilarfgeinumber offlc'arhon atoms,:ior'.examp1e 8.t0

.l2icarbonatoms.

k'IThe. substituted .dicarboxylic acids employed. in

I .preparing .therneweantiec'orrosion. agents are all .derivatives of the homologous .series ,of which -malonicacidis the.'firs't.member. .Higher acids .of .this' :series include succinic,,imaleic, 'glutaric, .adipic pimelic,..suberic,,azelaicand .sebacicacids,

.decane dicarboxylicacid, undec ane-dicarboxylic .acid etc. The-substituent may .beany hydrocar- .ebon rad-ical .andpreferably contains at least 6 carbon atoms. .Examples ofqsuchsubstituents inrcludeg-alk-yl and -.-alkeny1--;groups of any chain .-length;aryl groupsresuchaasyphenyl, tolyl, x'ylyl, A j.ibutylphenyl,naphthylyxenyl, etc. aralkyl groups, isuchzas-benzyl', phenylwethyl, fmethylbenzyl, etc.

iandicycloalkyl-gsuch.:as :cyclohexyl, .methylcyclo- .Mix- .tiires pf *;dicarboxylic acids :containing different 'n'ubstituentsmay likewisebe employed.

"' lhe organic nitrogen compounds which may I. Aliphatic and cycloaliphatic amines, such as:

. Methylamine Ethylamine Diethylamine' Amylamine Ethanolamine Diethanolamine Isopropanolamine Laurylamine Ethylene'diamine 0 '-Diethylenetriamine 1. Triethylenetetramine L2; .Gyclohexylamine 13. Dicyclohexylamine II. Aromatic amines, such as:

'1. Aniline Naphthyla-mine Methylaniline- 'Di'ethylanili'ne Tolui'dine i Phenetidine Diphenylamine 1 Diamino=diphenylmethane -Amino-phenol "AminO-.CI"SO1 Phenylenedi'amine :Benzidine "Amino diphe'nyl nmino diphenyloxide -'Acetanilide '16. .Chloram'line IIIJHeterocycl ic 'amines and ni-trogen bases,

suchas:

. MorphOline vPiper-i'cline i Amino -benzotfiiazole- 'i Phenothi'azine 'JFur-ami'de *O'xazolin'e cbcoqcngn acdmhmmamwcsooo-qmcnibcow assass n Anyof theabove, .ormixtures-thereoi. or vari- .ous .oxygen, halogen, .sulfur,. nitrogen. or. .phos- ,phorusrderivatives of these -compounds may be reacted with the above-defined .class ,of dicarboxylic -acids .to .form .the. anti-corrosion agents .e'mp1oyed;in mineraloil-compositions in.acco1fd .ancewiththeinvention.

The nitrogen compounds of the above groups that .can be employed in preparing the .ami'des .,..or-imides1naybe terniedprimaryor secondary amines as .-they contain .at least .one hydro atom attached to an amino nitrogen-atom.

Theflmineral .oil compositions .ofjthepresent invention mayube of various typeshaving special properties adapting them .ior -certain particular applications. Thus, .theytmay helubricating .oil compositions ranging from .light .machine and household oilst0-heavy lubric'antslfor-large internal combustion engines-including diesel ..en-

gines. Alternatively, they.maylbe..of' thenature of ,.protective oils .or greases such as .slushing 1 oils .or .gun, greases, .or they maybe. adapted. for

.use. as. metal working. oils .or the like. "Theyare particularly .well suitediornseas steam turbine .oils since they provide .adequate protection against ..rusting .and corrosionin the presence of Water and water -vapor, :and do .not .readily emulsify with water. Theylmay also. be fuel oil compositions, -including diesel engine -fuels=and 5 domestic burner oils, Whereby -the 'antiw'corrosion :agent protects ithe tanks in which .such. coil 'is stored against corrosion .br-ought; ziaboutmy :the

be reacted with the above-defined-dicarboxylic Water with which-511cm oils-are oftencontamihated-as for example in the case ofmarine fuel oils which usually are contaminated with salt water, giving rise to veryserious corrosion 'in the storage bunkers.

Regardless of the particular type of composition or the specific use to which it is adapted, the new compositions of the invention are prepared simply by mixing the herein-defined anticorrosion agents with the desired mineral oil base to for-m a homogeneous composition. These agents function independently of other common oil additives, e. g., anti-oxidants, detergents, viscosity index improvers, anti-foam agents, demulsifying agents, pour point depressants, etc, and accordingly may be used in conjunction with such additives. They may be employed in varying amounts depending upon the severity of the corrosion conditions under which the composition will be used. Ordinarily, however, lubricating compositions contain less than about 1 per cent, usually between about 0.01 and about 0.5 per cent,of the anti-corrosion agent, based on the weight of the base oil, whereas slushing oil types of compositions may contain upto or more per cent by weight of the corrosion inhibitor to provide adequate protection against corrosion during storage for lon periods of time under very drastic climatic conditions.

In testing and demonstrating the efiiciency' of the new compositions in providing protection against corrosion, use may .be made of the socalled ASTM Corrosion test which is a modification of that specified in th AS'IM Standards on Petroleum Products and Lubricants, September, 1945, designated as ASTM D-665- l4T. In brief,.this test consists in placing a 30011111. sample of the oil or oil composition to bel'tested in a 400 ml. beaker which is immersed in a constant temperature bath maintained at 140 F. The beaker is fitted with a cover provided with openings for a stainless steel motor-driven stirrer and for insertion of a standard steel test bar, /2 inch in diameter and 5 inches long, which has been very carefully cleaned and polished just prior to the test. The stirrer is started and when the oil sample in the beaker reaches a steady temperature of 140 F. the test bar is inserted in the proper opening and hangs suspended from the beaker cover. After minutes of stirring, 30 ml. of distilled water are added to the-beaker, and stirring is then continued for 48 hours, after which time the test bar is removed and examined for rustspots. If there are no rust spots onthe steel bar, the sample is said to pass this test. Any rustingof the bar indicates failure. I

Ina modification of the above-described test, artificial sea water having the following composition:

Parts by weight NaCl 25.0 MgClz 61-120 1 1.0 Na2SO4 4.0 CaClz 1.2 Distilled water 1000.0

is used instead of the distilled water. This test is referred to as the Salt Water Corrosion test and provides an evaluation of the composition under very drastic corrosion conditions.

The following examples will illustrate several ways in which the principle of the invention has been applied, but are not to be construed as limiting the same. Unless otherwise stated, the oil compositions prepared and tested as described in these examples consisted only of the anti- 6 corrosion agent and a refined lubricating oil having I the following specifications:

Approximately 18.5 parts by weight (1 mol) of a technical grade of dodecylamine were added in small increments to approximately 18.6 parts by weight (1 mol) of alpha-cyclohexyl-malonic acid.

During the addition of the amine, heat was the ASTM and Salt Water Corrosion tests.

evolved. The mixture was then heated to about 250 F. and maintained at this temperature for about 5 minutes. Upon completion of the reaction the amido reaction product was obtained as a yellowish wax-like solid. A composition consisting of 0.05 part by weight of this product and parts by weight of the above-described base oil'successfully passed both of the hereinbefore-described corrosion tests. The base oil itself failed to pass either of these tests as did a composition consisting of 0.05 per cent by weight of free cyclohexyl-malonic acid dispersed in the base oil. Heavy rusting of the steel specimen occurred in both cases.

Example II Approximately 18.5 parts by weight (1 mol) of technicaldode'cylamine were reacted with approximately 35.6. parts by weight (1 mol) of alpha-hexadecylmalonic acid as described in EX ample I. The amido reaction product obtained was a yellow waxy solid. A composition consisting of 0.05 per cent by weight of this product dispersed in the base oil successfully passed both A similar composition containing the free hexadecylmalonic acid failed the Salt Water Corrosion test.

Example III Approximately 87.6 parts by weight of mixed alkenyl-succinic acids in which the alkenyl substituents contained an average of 10-12 carbon atoms were reacted with approximately 510 parts by Weight of diphenyloxide in the presence of aluminum chloride to obtain a thick viscous liquid product consisting of mixed (phenoxyphenyl-alkyD-succinic acids in which the alkyl groups contained an average of 10-12 carbon atoms. Approximately 45 parts by weight of this product were treated with 0.! part by weight of butylamine as described in Example I. The amido reaction product obtained was a darkbrown viscous liquid. This product was incorporated in the base oil in an amount of 0.10 per cent by weight. The resulting composition passed the AS'I'M and Salt Water Corrosion tests, whereas a composition containing the same amount of mixed (phenoxy-phenyl-alkyl)-suc cinic acids failed both of these tests.

Example IV Approximately 27.0 parts by weight of mixed alkenyl-succinic acids in which the alkenyl substituents contained an average of 1012 carbon atoms were mixed with approximately 18.1 partsv by weight of dicyclohexylamine, and the mixture was warmed slightly to promote reaction. The

mixture" was-heated to about 250 F. .and'iwwas maintained atv this temperature-for about -5":min'- utes. Upon. completion of the reaction theamido reaction product obtained was' a light-yellow sticky solid reaction product." This product "was incorporated in the base oilin amount' 'of 0.05

per cent by weight. The resultin'g'composition successfully passed the" San water ccrrosicn test, Whereas a composition consisting? of -th'e sameamountof the free alke'nyl suc'cinic acid dispersed in the base oiliailedthistesti Eramp'l'v p, Approximately equi-molecular "proportions of 'alpha-n-octyl-nonanedicarboxylic"acidandtech nical hexadecylamin'e-were reacted "as de'scribed in Example-:1. Thereaction productobtained was a light yellow' 'waxyfsolidf This product was incorporatedin' the b'aseo'il in amountof 0.'05"per cent by weight to obtain" an -oil compos-ition which successfully'passed'the ASTM-C6r rosion-test."

Eiv'amp'Zef-VI' Y Approximately 19.8 partsTby; weight T of=- cyclohexylamine (2 mols) were addedin-small-incre ments toapproximately 27.0 partsby weight (1 mol) of mixed alkenyl-succinic acid-anhydrides. The latter materiabwas alight-yellow, oily-liquid; commercial product consisting of a mixture 1 of alkenyl-succinc: acidanhydrides in which the alkenyl substituents contained-an average of from about 10 to 12 carbon atoms. The mixture was heated to about 250 F. for about .-5 minutes... whereby reaction toiorm the corresponding amido product took place .re'adily. The .amido. reaction productwasa veiyviscous, clear, amber liquid. A composition consisting .of 0.10per cent byweight of thismproduct dissolved in the base oil .Was subjectedIltotheASTM and Salt Water Corrosion tests; Thiscomposition passed both tests, whereasa.compositionconsisting of "0.10 per centof the alkenyl-succinic acid anhydride itselfdissolved in the base oilfiailed both tests.

This application is a continuatio'n-in-part'of my co-pending applications serial No. 708,183 and Serial No. 708,186,"fi1ed on November 6, 1946 andnow abandoned. 7

Other modes: of applying: the pri-nciple of 'iny invention maybe' employed instead of those" ex-'- plained, change being madeas' regards the methods or materials "employed, provided the products defined by any 'of the-followingcla'i-ms be obtained; v I claim: I 1'. 'An improved mi'neraloil cb'rnlibsitionfcdni prising-:a-major amount-oflamineral oil and-a minor. amount of an amide'of dodecylamine and an acid selected-from the group consistingvof alpha-cyclohexyl malonic acid and alpha-hexadecyl malonic acid, the amount of said amide beingfsuflicient to impart corrosion inhibiting properties to said composition.

2. An improved mineral oil composition'comprising -a major amount of a mineral oil and a minor amount ofv an amide of dodecylamineand alpha-cyclohexyl malonic acid, the amount of said amide-beingsufficient to impart corrosion inhibiting properties to said composition.

3. An improvedmineral oil compositionicom- 'prising amajor amount of a mineral oil-and a minor amount of an' amide-of dodecylamine-and alpha-hexadecyl malonic acid, the 1 amount of said amide being; sufficient to impart corrosion inhibitingrproperties to said composition.

4.-An improved mineral oilv composition comprisinga major amount of a mineral oil and a minor amount of theamide which is formed by reacting about equimolecular amounts of a'basic organic amine having at least one hydrogenatom attached to the amino nitrogen atom and a ALBERT G. ROCCHINI.

REFERENCES CITED The-followingreferences are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 2,109,941 DAlelio Mar. 1, 1938 2,342,114 Blair et a1 Feb. 22, 1944 2,412,557 Blair et al Dec. 17, 1946 2,412,708 Blair et a1. Dec. 1'7, 1946 2,417,833 Lincoln et al Mar. 25, 1947 2,466,530 Blair et a1 Apr; 5, 1949 2,481,585 Freeman Sept. 13, 1949 2,490,744 Trigg 'et a1. Dec. 6,1949 

5. AN IMPROVED MINERAL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL OIL AND A MINOR AMOUNT OF THE AMIDE WHICH IS FORMED BY REACTING ABOUT EQUIMOLECULAR AMOUNTS OF A BASIC ORGANIC AMINE HAVING AT LEAST ONE HYDROGEN ATOM ATTACHED TO THE AMINO NITROGEN ATOM AND A MALONIC ACID HAVING AN ALKYL SUBSTITUENT OF AT LEAST SIX CARBON ATOMS, THE AMOUNT OF SAID AMIDE BEING SUFFICIENT TO IMPART CORROSION INHIBITING PROPERTIES TO SAID COMPOSITION. 